Access portals, or ports, provide a convenient method to repeatedly deliver medicants to remote areas of the body without utilizing surgical procedures. The port is totally implantable within the body, and permits the infusion of medications, parenteral solutions, blood products, and other fluids. The port may also be used for blood sampling.
Known ports typically include a chamber accessible through a self-sealing septum. Septums of the prior art vary in shape, from a wafer-like cylindrical block of silicone to a pre-molded septum of U.S. Pat. No. 4,802,885 to Weeks et al. The pre-molded septum of U.S. Pat. No. 4,802,885 includes opposed convex surfaces and a peripheral ledge.
In common practice, a caregiver locates the septum of the port by palpitation. Port access is accomplished by percutaneously inserting a needle, typically a non-coring needle, perpendicularly through the septum of the port and into the chamber. The drug or fluid is then administered by bolus injection or continuous infusion. Ordinarily the fluid flows through the chamber, into a catheter and finally to the site were the fluid is desired.
Except for the septum, traditional ports are constructed from all-metal or all-plastic. Each type of construction has unique advantages and disadvantages.
All-metal constructions have the advantages that they maintain a septum in a self-sealing fashion after repeated percutaneous injections. Additionally, all-metal constructions, such as titanium, or stainless steel provide a port which is both biocompatible and compatible with the injected fluid.
However, all-metal constructions present the disadvantages that they are relatively heavy, difficult to fabricate and relatively expensive. Additionally, all-metal ports produce large Magnetic Resonance Imaging (MRI) artifacts.
On the other hand, all-plastic ports have the advantages that they are inexpensive to construct, light in weight, and do not create an MRI artifact. However, ports constructed from plastic have the disadvantage that infused fluids may react with the plastic body of the port. All-plastic ports contain the disadvantage that they cannot maintain a sealing engagement with the septum after repeated percutaneous injections. Additionally, all-plastic ports are susceptible to nicks and scratches on the interior surface by the accessing needle. These nicks and scratches could lead to nidus, blood clots, or precipitation formations.
Efforts have been made to combine the advantages of all-metal ports with all-plastic ports. For example, in U.S. Pat. No. 4,802,885 to Weeks et al., a metal reservoir having a chamber sealed by a pre-formed silicone septum is jacketed by a single piece of a silicone elastomer. However, all-metal ports jacketed by a single piece of elastomer have significant shortcomings. These shortcomings include quality control problems during manufacturing, and expensive molding processes.
Other efforts have focused on providing a multiple piece all-plastic housing in cooperation with an open metal cup to sealingly engage a septum. For example, see U.S. Pat. No. 5,213,574 to Tucker. This design has shortcomings associated with it, including defects in the plastic housing which may cause an improperly sealed septum. Once the septum is improperly sealed the entire port must be discarded.
Therefore a need has arisen for an access port device which addresses the problems of prior port devices.